1. Field of the Invention
This invention describes the use of recombinant DNA technology for the design and synthesis of novel modified interferons. More specifically the invention relates to interferons not known in nature, which are intended for use in viral and neoplastic diseases, and immunosuppressed and immunodeficient conditions, as they exhibit new and unexpected biological properties.
2. Description of the Prior Art
The interferons are a class of proteins that occur in vertebrates and act as biological regulators of cell function which include increasing resistance to pathogens, limiting cell growth and modulating the immune system. The most studied property of the interferons is their ability to convert cells into an "antiviral state" during which they are more resistant to virus replication (Lengyel, Annual Review of Biochemistry, 51, 251, 1982). In addition to conferring antiviral resistance to target cells, interferons (IFNs) have antiproliferative (antigrowth) properties (Stewart, 1979, The Interferon System, Springer, Berlin). It has clearly been shown that interferons produced naturally act as antiviral and antiproliferative agents (Gresser et al., Biochim. Biophys. Acta, 516, 231, 1978; J. Exp. Med., 144, 1316, 1976).
The IFNs, by virtue of their antigenic, biological and physico-chemical properties, may be divided into three classes: type I, IFN-.alpha. ("leucocyte") and IFN-.beta. ("fibroblast"); and type II, IFN-.gamma.. Human IFN-.alpha. is specified by a multigene family comprising at least 20 genes. The classification of IFN.alpha. and IFN-.beta. as type I interferons is in part determined by their significant degree of homology, 23% at the protein level (Taniguchi et al., Nature, 285, 547, 1980).
While the mechanism of action of interferons is not completely understood, certain physiological or enzymatic activities respond to the presence of the interferons. These activities include RNA and protein synthesis. Among the enzymes induced by interferons is (2'-5'). (A)n synthetase which is activated by double-stranded RNA. This synthetase generates 2'-5' linked oligonucleotides, and these in turn activate a latent endoribonuclease, RNAse L, which cleaves single-stranded RNA, such as messenger RNA (mRNA) and ribosomal RNA (rRNA). Also induced by IFNs is a protein kinase that phosphorylates at least one peptide chain initiation factor and this inhibits protein synthesis (Lengyel, ibid, p.253). IFNs have been shown to be negative growth regulators for cells by regulation of the (2'-5')An synthetase activity (Creasey et al., Mol. and Cell Biol., 3, 780, 1983). IFN-.beta. was indirectly shown to be involved in the normal regulation of the cell cycle in the absence of inducers through the use of anti-IFN-.beta. antibodies. Similarly, IFNs have been shown to have a role in differentiation (Dolei et al., J. Gen. Virol., 46, 227, 1980) and in immunomodulation (Gresser, Cell. Immunol., 34, 406, 1977). Finally, IFNs may alter the methylation pattern of mRNAs and alter the proportion of fatty acids in membrane phospholipids, thereby changing the rigidity of cell membranes.
These and other mechanisms may respond to interferon-like molecules in varying degrees depending on the structure of the interferon-like polypeptide. Preliminary evidence (U.K. Patent GB 2,090,258A) suggests that members of the multigene IFN-.alpha. family vary in the extent and specificity of their antiviral activity (Pestka, ibid.) For example, combination of IFN-.alpha.A with IFN-.alpha.D resulted in "hybrid" genes which show antiviral properties that are distinct from either parent molecule (Weck et al., Nucl. Acids Res., 9, 6153, 1981). However, hybrid human IFNs with substantially increased human cell activity/specificity have not yet been developed. One Patent Application has been published describing IFN-.beta./.alpha. hybrids (PCT/US83/0077). This patent is an initial attempt to form modified IFNs, however, they do not disclose the substantially modified structures or activity of the present invention.